Conventionally, this type of strobe device includes a flash discharge tube for emitting light, and a reflector for reflecting the light emitted from the flash discharge tube toward a photographic subject.
Normally, a thin conductive film configuring an external trigger electrode is provided on the flash discharge tube around its outer peripheral surface, in order to facilitate lighting.
By applying trigger voltage from, for example, an external circuit to this thin conductive film, which is the external trigger electrode, a discharge path is formed inside the flash discharge tube and the light is emitted from the flash discharge tube.
However, in the strobe device as configured above, there is a disadvantage that the thin conductive film absorbs the light emitted from the flash discharge tube. In addition, since the discharge path is not stable, due to a large movement (fluctuation) of discharge path at every emission of light inside the flash discharge tube, an amount of light emitted from the flash discharge tube varies or light distribution varies.
To solve the above disadvantages, the following flash discharge tube is proposed (e.g. PTL 1).
In the flash discharge tube in PTL 1, the outer peripheral surface of the flash discharge tube is closely attached to a reflector (conductive reflector), and a trigger lead wire is connected to the reflector, so as to use the reflector as the external trigger electrode. This omits the use of the thin conductive film conventionally formed on the outer peripheral surface of the flash discharge tube. Accordingly, a disadvantage of absorbing the light emitted from the flash discharge tube is solved.
On the other hand, there is an increasing demand for a strobe device that can emit light with a small light quantity by making the flash discharge tube emit light for a short period. When the flash discharge tube emits light with a small light quantity, the discharge path needs to be further stabilized by suppressing movement of discharge path at every light emission, in order to suppress variation in light quantity and variation in light distribution of light emitted from the flash discharge tube.
However, the flash discharge tube in PTL 1 does not disclose the closely-attached state of the flash discharge tube and the conductive reflector. Therefore, when the flash discharge tube emits light with a small light quantity, unignorable variation in discharge path may occur, depending on the shape of conductive reflector. As a result, variation in light quantity and variation in light distribution of light emitted from the flash discharge tube cannot be sufficiently suppressed.